Hydraulic press



H. MLLER HYDRAULIC PRESS Oct. 24,

5 Sheets-Sheet 1 Filed Nov, 7, 1956 oct' 24, 1961 H. MOLLER 3,005,431

HYDRAULIC PRESS Filed NOV. 7, 1956 5 Sheets-Sheet 3 1&3.

Ul NIU l IM IUI u :1 ZZer 3g? @9 m United States @hice Patented Oct.24., 1961 Claims priority, application Switzerland Nov. 10, 1955 1Claim. (Cl. 113-44) This invention relates to hydraulic presses for theforming of sheet metal blanks, comprising a press table carrying aforming tool `and a press head adapted to be raised and lowered and tobe locked in lowered position, and a hydraulic forming attachmentcarried by the press head and located centrally above the forming tool.The hydraulic forming attachment comprises a cylinder with a workingpiston slidable therein and which opens.

downwardly into a liquid receptacle. The bottom of the liquid receptacleis closed by an elastic wall, and the piston is adapted to place theliquid in the receptacle under pressure and thereby press, by means ofthe elastic wall, a sheet metal blank inserted between the receptacleand the forming tool to the shape of the forming tool. The press of thisinvention is characterized by the fact that the hydraulic formingattachment is located in the press head and the working piston extendsupwardly into a pressure chamber formedrin the press head, in whichchamber fluid under pressure may be introduced when the press head islocked in its lowered position, to exert downward force upon the piston.

In the following description, the invention will be more specificallydescribed with reference to the attached drawings, in which:

FIGURE 1 is a perspective, sectional View of one embodiment of theinvention;

FIGURE 2 is a View of the locking mechanism by which the press head isreleasably secured in its lowered position, said view being partially inhorizontal section and partly in plan; and

FIGURE 3 is a fragmentary view of the bottom portion of the press,partly in side elevation and partly'in Vertical section.

The press of this invention generally comprises a press table 1, a presshead 2 with a hydraulic forming attachment, a balance cylinder unit 3, apressure cylinder unit 4, columns 5 with locking means 6, andanup-pressure device 7.

The press table 1 has a number of vertical holes 10 y therethrough inwhich .pressure pins llvare axially slidable, and it carries an annulartool holder of ring 12 which encompasses a forming tool 13. The presshead 2 is vertically slidably guided on the columns 5 and is arranged tobe retained in its lowermost position by the locking means 6. In thebottom of the press head there is a downwardly opening well or liquidreceptacle 14, closed at its bottom by a wall 15 of rubber or similarelastic material. The wall 15 is part of Va rubber cup having a rim 16which is sealingly secured in an annular groove 17 in the inside of thewell or liquid receptacle 14 to fasten the wall 15 in place. The upperportion of the well or receptacle comprises a cylinder 18 which opens atits top into a cylindrical pressure chamber 19 having a larger diameterthan'that of the cylinder 18. Axially slidable in the cylinder 18 is aworking piston 20 which extends upwardly into the pressure chamber 19and has at its upper end a head 21 fitting in the pressure chamber. v

To obtain a iiuid-tight seal between the piston and the upper cylinderportion 18 of the well or liquid receptacle 14 there is an annulargroove 22 in the inside of the cylinder, in whichV is seated a U-shapedelastic gasket 23 engaging the piston, the'inner portion of the U facingdownwards and communicating through one or more channels 24 with theliquid receptacle 14. The working piston is forced downwards byhydraulic uid vunder pressure, which is introduced into the upper end ofthe pressure chamber 19 via a pipe line 25 from a suitable source, andwhich acts uponthe upper surface of the piston head 21 to thereby imposepressure upon the liquid in the well or receptacle 14 and thus in turn,

cause the elastic wall 15 to force a sheet metal blankv 26, positionedunder the wall, down into the forming tool 13.

'Ihe upward movement of the piston 20 is obtained by a pressure fluid,preferably compressed air, which is introduced from a source thereof viaa line 27 into the lower part of the pressurechamber to act upon theunderside of the piston head 21.

The balance cylinder unit 3 serves to balance and raise the press head 2with the hydraulic forming attachment described above, and it comprisesa stationary,V

closed balance cylinder 28 mounted on the columns 5 and having movablymounted therein a balance and raising piston 29, from which the presshead 2 is suspended by means of a plunger rod 30. The balancing andraising of the press head with the forming attachment thereon isprovided for by introducing pressure iluid, Ypreferably compressed air,vfrom a source thereof via a line 31 intothe balance cylinder to actupon the underside of the` piston 29, the upper part of the balancecylinder communicating with ythe open air through a line 31.

The lowering orf the press head with Vthe forming attachment is effectedby means of the pressure cylinder unit `4 comprising a comparativelysmall pressure cylinder 32 fitted on the top of the balance cylinder 28and having a pressure piston 33 movable therein. The piston33` isconnected to the balancing and raising piston. 29 by avr plunger rod 34extending coaxially through the balance cylinder. A pressure uid isintroduced via a line 35 into the upper end of the cylinder 32 and actson Vthe upper side of the piston 33 thereby overcoming the pres sure thebalance cylinder 28, whereby the press head 2 with the formingattachment is pressed down. vWhen `the press head has reached its lowerposition it is` locked in place by the |locking means 6, whereby thereaction pressure `from the Well or receptacle 14' is absorbed by thecolumns 5 via the locking means.

The locking means 6 are operated by a double acting cylinder pistonassembly 36, and consist of pairs of jaws 37 and 38 arranged to be movedto and from a locked position in which they embrace each one of thecolumns 5 immediately below an adjustable nut 39 by means of Y which theposition of the press head is adjustable. Each' adjustable nut 39 may besecured in any desired position of axial adjustment by means of alocking nut 40. The jaws 37 land 38 `are each pivoted on a pin 41 and 42and provided with toothed segments 43 and 44 'respectively, coaxial withthe pivot pins, by which the movements of each of lthe pairs of the jawsare controlled. One of the jaws 37 has a lever 45, the outer end ofwhich is connected to a turn-stile 48 by means of a link-arm 47adjustable in length by means of a nut 46 and connected to the lever 45andl to the turn-stile 48 by means of pivot pins 49. The turn-stile 48is rotatably carried on the plunger rod 30 and receives its rotationalmovement from lthe cylinder piston assembly 36.V

When the press head is raised Iabove its lowermost s position, the jaws37 and 38 are swung apart, about their pivot pins 41 and 42, to clearthe adjusting nut@ 39 and lock nut y40. When the press head -2 hasreached its lowermost position, a pressure fluid is introducedv througha line 50I into one end of the cylinder piston means of the lever 45 andthe toothed segments 43 and 44, into positions gripping the columns 5.Opening of the locking means 6 is don-e by admitting the pressure iluidinto the other end of the cylinder piston assembly via a line 51.

The up-pressure device 7 comprises a cylinder 52, a piston 54 slidablein the cylinder, and a pressure disc 55 Supported on the piston S4 andv0n which the bottom ends of the raising pins 11 rest. In the bottom ofthe cylinder 52 there is a check valve 56 and a pressure regul'atingvalve 57. InV addition, the piston 54 has a plunger rod 58 connected tothe piston 67 of a locking device 59'.

The up-pressure device 7 acting th-rough* the raising pins 11, exertsthe necessary blank holding pressure upon a blank holding ring 81,described hereinatter, and can also serve to raise the forming tool 13out of its position in the tool holder 12.

The necessary pressure on the raising pins is obtained in the followingmanner. From a source of oil under pressure, such as an accumulator, oilis permitted to enter the cylinder 52 via a line 60, a channel 61 andpast a check valve 56. The prevailing pressure of the oil will thus beexerted on the bottom surface of the piston 54 and the resultant liftingof the raising pins is utilized as above stated when moderate blankholding pressures are required and to raise the forming tool L13 out ofthe tool holder 12 when needed. When a higher blank holding pressure isrequired, this is provided by admitting compressed air through anotherline 63 connected to the pressure regulating valve 57.

The pressure generating means consists of a pressure intensifyingplunger 65 working in a cylinder 64. The outer end of the plunger, whichis exposed to the compressed air entering through line 63, has a largerdiameter than the inner end, which is exposed to the oil pressure in thecylinder 52 through -a bore 66 made in the wall of cylinder 52 andproviding a seat 66', against which the inner end of the plunger isarranged to seat. Iff plunger 65 is seated, oil can return through line60 from beneath piston 54 only if a suiiicient downward force is exertedupon pis/non 54 to unseat plunger 65, that is, the pressure which piston54 imposes upon the oil in the cylinder 52 must be great enough toenable the oil to'overcome the force of the air pressure acting on thelarge diameter end of plunger 65, to permit the oil to ilow into line 60through bore 66, since otherwisethe check valve 56 prevents reverseA:How of such oil back through the channel 61.

The locking device 59 of the up-pressure device 7 is needed when thelatter has to be locked at its lower limit of travel during a certainperiod of the upward movement of the press head 2. At its lower end, theplunger rod 58 is provided with a piston 67, sealingly but slidably:fitted in a cylinder 68. The lower end of the cylinder 68 is closed bymeans of a cover 69 and is lled with oil, the cylinder being connectedto a second pressure regulating valve 72 through bores 70 and 71 in thewall of the cylinder. Similarly toi the regulating valve 57, thepressure regulating means in valve 72 consists of a pressureintensifying plunger 73 slidable in a cylinder 74. The outer end of theplunger 73 is enlarged to provide an increased pressure area, which isadapted to be acted upon by compressed air admitted into the cylinder 74through lines 75 and 76 while the inner end of the plunger has Aasmaller area, which is arranged to engage a seat 77 in the bore 70 andthereby close the latter.

The locking device A59 of the up-pressure device 7 operates in thefollowing manner. When the up-pressure device 7 is in its uppermostposition, the oil quantity lling the cylinder 68 is under the piston 67.Upon the descent of the up-pressure device, the piston 67 is moved downby the plunger rod 8, whereby the oil under the piston 67- is forced'viathe bore 70, the valve seat 77 and the bore 71 to the cylinder spaceabove the piston 67. During this time, the line 75 serves as an exhaustand air under pressure is fed into the line 76 to thus actuate theplunger 73 to its outer position in which it leaves the valve seat 77open.

When the up-pressure device 7 -has reached its lower limit of travel,the line 76r serves as an exhaust and compressed airis fed into line 75.This causes the plunger 73 to be moved into sealing, engagement with thevalve seat 77, in which position it prevents the oil in the cylinderspace above the piston 67l from passing'through the bore 70, whereby theup-pressure device .7 is locked in its lowerrnost position.

It will be seen that when one of the lines 75 and 76 has compressed airfed thereinto, the other is used as an exhaust, and the position ofplunger 73 vn'll be determined by whichever of those two lines hascompressed air fed into it. Control of lines 75 and 76 is provided bymeans of a valve 78 connected with said lines and with another line 79which is connectable with a source of compressed air. The valve 78 canobviously be actuatedV by a solenoid or other automatic means, and inany event it provides for locking of the up-pressure device at timeswhen the press head 2' is moving upwardly from its lower limit oftravel, such locking being eifected' by seating of the plunger 77` toprevent iiowv of oil from one side of piston 67 to the other. If theup-pressure device were not locked down while the press head was rising,the blank holding ring 81 would be forced upwardly by the pressure pins11, pressing the newly formed part against the elastic wall d5 andtending to deform the part. However, when the press head nears the upperlimit of its rising movement, the valve 78 provides for reversal of theconnections to lines 75 and 76 by which the plunger 73 is unseated,permitting oil to flow through the bore 70 and passage 71, and thuspermitting movement of piston 67 In my United States Patent No.2,761,405, is shown and described a hydraulic forming attachment forpresses wherein a conventional die having a cavity is used. As willappear from the drawing, the present embodiment of the hydraulic presscomprises a specific arrangement of the forming tool I3 for deep drawingof sheet metal blanks. 'Ihe tool arrangement comprises a rigidstationary tool part or punch 80,. which is attached to the press tableso as to project upwardly in thecenter of the annular bore in the toolYholder or ring 12, to be encircled by a movable tool part or blank.holding ring 81, the: latter being guided for up and down movement byslidably fitting in the `annular tool holder. Normally,.the movable toolpart or blank holding ring is supportedby the pins 11 in a position atwhich its top sur-face is ilush with the top of the tool holder, butduring theforming operation the movable tool part or block holdingringis pressed down into the tool holder against the yielding resistanceoiered by the up-pressure device 7.

It will be observed that the shaping of the blank is accomplished byrolling or pressing; down the blank over the rigid punch. and that the`ring 81 serves to yieldingly support, by means of the pins 111, theblank 26 in its lgradual downpressing movement over the punch.

Having described only one preferred embodiment of the invention, I donot wish toy be .limited to the specific details set forth, but wish toreserve to myself any variations or modifications that may appear tothose skilled in the art and fall Within the scope of the followingclaim.

I claim:

In a press for forming sheet metal: a xed press bed; a press headmounted above the press bed between a lowered press-closed and raisedpress-open position; an annular tool holder on the press bed; a maleforming tool supported on and projecting up from the press bed insidesaid annular tool holder, withL the top thereof no higher than the topof the holder; a movable tool part vertically slidably tted in saidannular tool holder for movement between la raisedposition at whichtthetop thereof is ilush with the top of the, annular tool holder to.support a blank l to be formed, to a depressed position inside theannular tool holder, said movable tool part being apertured toaccommodate the station-ary male forming tool; fluid pressure meansbelow the press bed to yieldingly support the movable tool part andresist depression thereof into the annular tool holder, said uidpressure means including a plurality of pins vertically slidable throughthe press bed and bearing against the underside of the movable toolpart; means on the press head defining a shallow downwardly openingcylindrical well coaxial with the annular tool holder and of a diameterno greater than that of the tool holder; an elastic membrane fixed tothe head and extending across the mouth of the well to close the same;means in the head defining a vertical working cylinder above and spacedrom the inner end of the well, land a coaxial bore substantially smallerin diameter than said Working cylinder connecting the Well and theworking cylinder; a piston slidable up and down in the working cylinder;a plunger xed to ythe underside of the piston and slidably titted intothe bore; the elastic membrane, the walls of the well and the lower endof the plunger providing a liquid-tight chamber; a liquid lilling saidchamber; means on the press to move the press head from its raisedpress-open position affording Iaccess to the tool holder and permittingthe placement of a blank thereon, to its lowered press-closed positionin which the elastic membrane clamps the blank against the movable toolpart and coacts therewith to hold the blank during the forming thereofover the stationary m-ale tool part; means on the press to lock thepress head in its lowered press-closed position;

means on the press for introducing uid under pressure into the workingcylinder above the piston therein, to force it and the plungerdownwardly and thereby cause downward distension of the membrane withgreat force into said annular tool holder, so as to form the blank overthe male tool part, while the movable tool part coacts with the membraneto hold the unformed part of the blank; and means on the press tointroduce iluid under pressure into the working cylinder below thepiston therein, while venting uid from the cylinder above the piston, toforce the plunger upwardly and thereby release pressure in said chamberand return the membrane to its undistended condition.

References Cited in the file of this patent UNITED STATES PATENTS442,246 Chapman Dec. 9, 1890 464,737 Stapley Dec. 8, 1891 2,162,164Febrey June 13, 1939 2,394,636 Rode Feb. 12, 1946 2,409,254 ConzelmanOct. 15, 1946 2,584,339 George Feb. 5, 1952 2,605,731 Schulze Aug. 5,1952 2,696,183 Chyba Dec. 7, 1954 2,749,867 Engel June 12, 19562,754,786 Schulze July 17, 1956 2,761,405 Moller Sept. 4, 1956 2,766,711Dever Oct. 16, 1956

